全文获取类型
收费全文 | 98篇 |
免费 | 6篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 5篇 |
地球物理 | 36篇 |
地质学 | 47篇 |
海洋学 | 1篇 |
天文学 | 6篇 |
自然地理 | 8篇 |
出版年
2024年 | 1篇 |
2021年 | 3篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 7篇 |
2015年 | 3篇 |
2014年 | 1篇 |
2013年 | 2篇 |
2012年 | 3篇 |
2011年 | 7篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 6篇 |
2007年 | 6篇 |
2006年 | 7篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 2篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1965年 | 1篇 |
1960年 | 1篇 |
1958年 | 1篇 |
1956年 | 1篇 |
1949年 | 1篇 |
1939年 | 1篇 |
1937年 | 1篇 |
排序方式: 共有104条查询结果,搜索用时 78 毫秒
31.
Souad Boubekraoui Michel Courteaud Maurice Aubert Yves Albouy Jean Coudray 《Journal of Applied Geophysics》1998,40(4):165-177
In order to investigate aquifers, several geophysical surveys have been carried out in the Baril area of the southern flank of Piton de la Fournaise volcano on Reunion in the Indian Ocean using audiomagnetotelluric (AMT), very-low-frequency (VLF) and self-potential (SP) methods. We present the results with emphasis on a comparison between SP data and the findings of geoelectric surveys. AMT soundings have indicated, from the surface downward, three layers: (i) resistive volcanic rocks, (ii) an intermediate resistivity layer, and (iii) a conductive basement attributed to a seawater-bearing aquifer. VLF measurements allow the mapping of the first layer apparent resistivity, and therefore its bottom, when the true resistivity is supposed to be isotropic and homogenous. When this assumption does not hold, only the SP method permits the mapping of this bottom. Because of the good agreement between the SP and electromagnetic results, we propose the SP method as the first tool that should be used in studying shallow hydrogeological structures in volcanic areas. 相似文献
32.
Soil moisture is a key hydrological variable in flood forecasting: it largely influences the partition of rain between runoff and infiltration and thus controls the flow at the outlet of a catchment. The methodology developed in this paper aims at improving the commonly used hydrological tools in an operational forecasting context by introducing soil moisture data into streamflow modelling. A sequential assimilation procedure, based on an extended Kalman filter, is developed and coupled with a lumped conceptual rainfall–runoff model. It updates the internal states of the model (soil and routing reservoirs) by assimilating daily soil moisture and streamflow data in order to better fit these external observations. We present in this paper the results obtained on the Serein, a Seine sub-catchment (France), during a period of about 2 years and using Time Domain Reflectivity probe soil moisture measurements from 0–10 to 0–100 cm and stream gauged data. Streamflow prediction is improved by assimilation of both soil moisture and streamflow individually and by coupled assimilation. Assimilation of soil moisture data is particularly effective during flood events while assimilation of streamflow data is more effective for low flows. Combined assimilation is therefore more adequate on the entire forecasting period. Finally, we discuss the adequacy of this methodology coupled with Remote Sensing data. 相似文献
33.
Antonin Van Exem Maxime Debret Yoann Copard Boris Vannière Pierre Sabatier Stephane Marcotte Benoit Laignel Jean-Louis Reyss Marc Desmet 《Journal of Paleolimnology》2018,59(3):297-308
Lacustrine sediments contain a wide range of proxies that enable paleoenvironmental reconstructions. For instance, charcoal can be used to document past fire regime changes. In order to analyse high-temporal- and spatial-resolution records, however, it is necessary to develop fast, low-cost and high-stratigraphic-resolution methods. We developed a new paleo-fire proxy by studying a lacustrine core from the Esterel Massif, SE France, an area affected by two recent fire events, in AD 1987 and 2003. For this purpose, we searched for charcoal deposited and preserved in the lake sediments by combining a number of complementary methods, including: classic macrocharcoal tallying, scanning spectrophotometry, scanning hyperspectral imaging and high pressure liquid chromatography analyses. Macrocharcoal quantification is efficient, but time-consuming, and only provides intermediate-resolution data (cm scale). Spectrophotometry, used classically to quantify colour, is very fast, provides high-resolution data (4 mm) and is non-destructive (core preservation). Hyperspectral data have the same advantages as spectrophotometry, but offer higher spatial resolution (64-µm pixel size) and higher spectral resolution (6 nm) for core logging applications. The main result of this research is based on hyperspectral analysis at very high stratigraphic resolution using the I-band index. This index usually measures reflectance values at [660, 670 nm] corresponding to the trough in red reflectance produced by Chlorophyll a and its diagenetic products. This [660, 670 nm] reflectance trough, however, is also affected by the presence of altered organic matter and decreases with altered organic matter such as charcoal particles. Charcoal effect on the reflectance of Chlorophyll a and its diagenetic products is identified on first derivative spectra by a characteristic pattern around 675 nm, which is also in agreement with the Chlorophyll a concentrations measured by high-pressure liquid chromatography and charcoal particles. The I-band index is hence suitable for detecting burned organic matter, by quantifying the dilution of the chlorophyll signal by the charcoal signal. Thus, this adaptation of the I-band index can be applied in fire reconstruction studies. 相似文献
34.
35.
36.
The geomagnetic field and secular variation exhibit asymmetrical spatial features which are possibly originating from an heterogeneous thermal control of the Earth's lower mantle on the core. The identification of this control in magnetic data is subject to several difficulties, some of which can be alleviated by the use of core surface flow models. Using numerical dynamos driven by heterogeneous boundary heat flux, we confirm that within the parameter space accessible to simulations, time average surface flows obey a simple thermal wind equilibrium between the Coriolis and buoyancy forces, the Lorentz, inertial and viscous forces playing only a secondary role, even for Elsasser numbers significantly larger than 1. Furthermore, we average the models over the duration of three vortex turnovers, and correlate them with a longer time average which fully reveals the signature of boundary heterogeneity. This allows us to quantify the possibility of observing mantle control in core surface flows averaged over a short time period. A scaling analysis is performed in order to apply the results to the Earth's core. We find that three vortex turnovers could represent between 100 and 360 years of Earth time, and that the heat flux heterogeneity at the core-mantle boundary could be large enough to yield an observable signature of thermal mantle control in a time average core surface flow within reach of the available geomagnetic data. 相似文献
37.
38.
39.
Padel Maxime Álvaro J. Javier Casas Josep Maria Clausen Sébastien Poujol Marc Sánchez-García Teresa 《International Journal of Earth Sciences》2018,107(5):1579-1601
International Journal of Earth Sciences - The volcanism hosted by the Ediacaran–Terreneuvian Canaveilles Group of the Eastern Pyrenees displays two distinct geochemical affinities: (1)... 相似文献
40.
Simon?Delattre Etienne?BalanEmail author Michele?Lazzeri Marc?Blanchard Maxime?Guillaumet Olivier?Beyssac Eiken?Haussühl Bj?rn?Winkler Ekhard?K.?H.?Salje Georges?Calas 《Physics and Chemistry of Minerals》2012,39(2):93-102
Vibrational properties of diaspore, α-AlOOH, have been re-investigated using room-temperature single-crystal Raman spectroscopy
and low-temperature powder infrared (IR) transmission spectroscopy. First-principles harmonic calculations based on density
functional theory provide a convincing assignment of the major Raman peaks and infrared absorption bands. The large width
of the Raman band related to OH stretching modes is ascribed to mode–mode anharmonic coupling due to medium-strength H-bonding.
Additional broadening in the powder IR spectrum arises from depolarization effects in powder particles. The temperature dependence
of the IR spectrum provides a further insight into the anharmonic properties of diaspore. Based on their frequency and temperature
behavior, narrow absorption features at ~2,000 cm−1 and anti-resonance at ~2,966 cm−1 in the IR spectrum are interpreted as overtones of fundamental bending bands. 相似文献